Improvement in leveling- and grading instrument



naar saar @anni Gtjijta HAMILTON E.- TOWLE,

vOli" NEW YORK,` N. Y.

Letters Patent No. 102,882, dated May 10, 1870.

IMPROVEMENT IN IIEVELING- AND GRADING INSTRUMENT.

The Schedule referred to in these Letters Ptent-and making 'paxt of the sa'me,

I, HAMILTON Ejlownnlof ANew York, in the county and State of New York, have invented cer-v talnmprovementsin Surveying Instruments, of which the following is a specification.

Nature and Objects of the Intention. l The object kof the said invention is tol simplify the construction. of aleveling instrument, by which'it may befurnished at a comparatively cheap rate, and be used with facility and exactitude by persons who may be destitute of professional experience, or unfitted by the want, of 'technical education for 'operating with such instruments as ordinarily constructed.-

. In additiontothe minor details of construction and-v adjustment, the rst of the said improvements consists ina'peculiar ball-and-socket joint in which a divided hallpossesses all the advantages ot' the ordinary joint with an entire ball, and .is entirely free.

from the jerky motion that is almost iuseperable from the-latter.

" With the ordinary joint the first motion requires a greater power to eect 'than a continuation ofthe movement,- andy the excess of power, when only a 'slight movementisv required, is likely to move theinstrunient'too far. Even when thc joint may have been carefully ground, the gumming of the lubricating material, or the presence of dust or grit, will soon destroy the effects of good workmanship.

The variations inftheresistancerequire variations in the force, which are difficult to determine, and renderthe adjustment afmatter of experiment instead oi` a matter of precision. By dividing the ball, however,

and placing aspring between the parts, the tension of the spring remains `practically unaltered,'and the resistance to the Smovement inthe socket is similarly uniform within the limit' adjusted by thc-`clainpscrew of the socket.

By dividing the'ball ati-ight angles to the axis that passes through the neck, and placing between the parts an axial spindle common to both parts, an effort to move the instrument around that axis is resisted only` by the friction on the small portion of the part of the ball annexed to the neck, that is, within thc socket,

and, as this is much less than the friction on the entire surface within the socket, say about one-fifth, for example, the instrument may be turned around the entire circle with one-fifth of the power that would he re- -quired to complete a revolution in any'ot-her plane in which both parts of the balhmust 4necessari1y be moved, and the diii'erenee betweenthese two extremes of the exercise'of power i's. sucient to insure aecuracy in the'V hands of even the most careless.

Thisimprovement in the construction ofvball-andsocket joints is applicable toall instruments and machines in which such joints may be used.

vAnother of the said improvements consists in the construction of tl1 e sights,'by which' they are mounted on screw-Shanks, the threads of which have a'deiinite relation to the distance between the sights.

Sights for any purpose usually consist of slides aib justed within frames by screws, and marked w-iththe.

The improvement in sights, not only for surveying instruments but for all applications of sights, consists in establishing the relation in the construction of the instrument, andindependent of subsequent adjustment, by means of revolving sights mounted on screw-Shanks in which the relation between the ad,- justment of the sight and the distance is determined' bythe thread, and is 'altered the same in amount,` either more or less, at each rotation of either of the. sights, and may be doubled by the rotation of bot-'h of them. For example, if the sights Aare ten 'inches apart, andthe threads are one-tenth of an inch in pitch, each revolution of one sight lalters the grade or level one f oot in a hundred, and the reverse revoln tion of the other sight continues the increment an equal amount to `give'the instrument a doubled range. A. half-revolution of course alters the grade but six inches in the hundred feet. The stems -or shanks ot' the sights are attened, so that, when held by a setscrew, the square en d of the screw sets thesight square, and the flattenedsidesfurnish a convenient place for the" marking of thegraduations.

In` levels, as ordinarily constructed, th-e adjusting'-, screw, in setting the level, liftsV the end of thefin'sttument, ,and it must be free to 'rise It; therefore, by any accidentthe instrument be turned upside down, the ,Y parts will swing apart, and may be strained,and perhaps injured. With the light instrument attainable I with these improvements, the weight ofthe bar in which t-he tube is secured may be carried on a spring, and

the adjustment may be eifected by means 'of a screw that restrains the springend holds the parts together in any position, operating, in` fact, in combination with the spring, in just the reverse mannertothe ordinaryv adjusting-screw that has no spring.'

Another improvement consistsm constructing a level with a woodserew, by which it'may be mounted on a stake, or otherwise, without a tripod. It is some-` times convenient to use theinstrument in places where there may. not be room enough for a tripod, as, for instance, close to a rock or wall. Wood screws have been hitherto essay'ed for the purpose simply of sc euring telescopic and other instruments in position,

but it is obvious that that they cannot be usedindependent of other adjustment in an instrumentto sweep around a horizontal plane. In combination with the divided ball above described, the wood-'screw may be used as eectively as any tripod with its comparatively complicated set-screwadj ustment, and, with its application toa leveling'instrument, a stake that may be driven close to an obstruction, where there would 0therwise be insnicientvroom, is the only support required.

Description of thc Drawings.

screw-stems, G, in the manner described, and secured in any position by theset-screws t'. I prefer to cementV the tube in asupplementary cup set with 'one or more screws inside a cavity in the bar, with the whole covered by the ordinary plate.

The bar, with the sights O and I, and the tube L, is carried on the joint J ,fand is sustained by the spring S, and held by the screw s` adjusted by the thumbscrew nut l. v

The wood-screw P carries the ball-and-socket joint, the socket part being made with a clamp and screw, in the usual way. The ball is divided, andhas a spring between the parts, and a small pin as an axis, common to both of them. y sired, with leather or'other material.

Claims. I claim as my invention- -4 'Y 1. A ball-.and-socket joint, with a divided ball, with or without an interposed spring, substantially as described, and either with or without an axial spindle.' 2.v 'lhe'combination and arrangement of the gradu-y ated adjustable sights, having screw-Shanks, the threads vof which have a determined relation to their position, with a leveling instrument for operation lsubstantially as described.

' HAMILTON E. TOWLE. Witnesses:

CHAs. E. FARNSWORTH, 1. W. FARNSWORTH.

The socket may be lined, if de- 

